Separation and settlement of solids and matters from sewage and other liquids



W. CLIFFORD.

SEPARATION AND SETTLEMENT 0F SOLIDS AND MATTERS FBOM SEWAGE AND OTHER LIQUIDS. APPLICATION FILED. MAR. 27. yIQIII.

1,343,764. Patented June 15., 1920 'WILLIAM CLIFFORD, OF OXLEY, WOLVERHAMPTON, ENGLAND, ASSGNR T@ JONES i & ATTWOOD LIMITED, 0F AMBLECOTE, STAFFRD, ENGLAND.

SEFARATION AND SETTLEMENT 0F SOLIDS AND MATTERS FROM SWAGE AND THER LlQUDS.

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Specification of Letters Patent. Pattgnted June 159 ggo Application filedv March 27, 1918. Serial No. 225,050.

To all .whom t may concern.'

Be it known that I, WILLIAM CLIFFORD,

-a subject of, the King of England, residing at UXley, Wolverhampton, in the county of lStafford, England, have invented new and useful Improvements in and Connected with the Separationand Settlement of Solids and Matters from Sewage and other Liquids, of which the following is a specification.

This invention has reference to the separation and settlement from liquids dealt with at sewage, or analogous liquid disposal works, or fromchemical and like manufacturing liquids, of the suspended matters from such liquids; and it is directed more especially-to the separation and settlement of' such substances from the liquids which have a specific gravity little greater than that of water, or which are light and of a character readily disturbed, and settlement whereof is impeded or prevented by currents in the liquid; at the same time, it is applicable to the treatment for separation of any liquids of the above character; but for convenience it will be described as applied to the separation of sludge from sewage or like liquids.

The invention has primarily for its object to provide improvements hereinafterdescribed in the settlement vor separation of suspended matters from sewage liquids, or chemical and like manufacturing liquids, and especially in cases wherethe suspended matters are relatively light or flocculent, suoli for instance, as the sludge resulting from the purification of sewage or like liquids by the process known as the activated sludge process; and it may be applied to systems wherein the How of liquid to be treated and the discharge of separated water is continuous, and also to settlement tanks working on the ll-and-draw principle to secure the more rapid quiescence of their contents. p

I have ascertained by a large number of experiments with the activated* sludge process, that the sludge produced is extremely prone to disturbance when settled, and that in settling tanks slight eddies or movement near it disturb and retard settlement of suspended matters, so that it is difficult' to obtain a complete separation and prevent particles of such sludge passing away with the eflluent. I have found that freshly activated sludge contains particles ot en` treme fiocculence of a density only very slightly greater than, water, and thus very difficult to settle; and even gentle current eddies will prevent these particles from being precipitated; and heretofore, it was found at times that particles of theV sludge were passing away with the effluent, due no doubt to obscure movements of small eddi due to causes such as the manner and direction of introduction of the liquid into the settling tank, and the How, or changes of direction of iow in the tank.

'lhus the conditions under which the complete separation of sludge from water, and a pure efiiuent can be brought about and exist; and on the other hand an imperfect separation, and slightly imperfect eflluent exist, may differ to only a very small extent,

4and that suoli an alternative condition is a matter of great nicety of the flow-controlling means, guidance of the liquid, and manner of introduction into and flow through the tanks; but the control and accomplishmentof the requisite conditions to produce the required and necessary result are nevertheless effected by simple, yet definite and small factors and means, arrangedv in defif nite Ways or manners, which result in the production of a definite manner of flow and behavior of the liquid inpassing through the tank.

For convenience, the form of tank in connection with which the invention will be first described, will be/one having an inverted conical or pyramidal bottom, with or without short vertical walls, anda cen tral downfiow inlet pipe,

ln sewage disposal works, the liquid from `which the solids or matters are to be set- 'and keep it in motion, and particularly in cases where the solids or matters are relatively light, this motion is inimical to the proper settlement. In practice I have found that the stream of liquid in flowingv down the pipe into the tank, although not visible tol sot

to the eye from above, does in fact, extend a long way down into the body of liquid; and with liquids of the character referred to it has the effect of disturbing the sediment-at or near the bottom of the tank, and starting the main body .of liquid into motion, with the eiect, that sedimentation or settlement of the solids or lmatters is not so complete andthe effluent is not of the purity required.

This action and the effect of the continuance of the flow of the 'influent into the' body of the liquid is under this invention prevented, and the method of accomplishing it consists in breaking up the inflowing stream where it enters the tank, and producing a distributed and relatively slow and quiet,

form of iow in a relatively large body of liquid; in some cases, causing it to eddy on itself at a suitable position intermediate the top and the bottom of the tank. y

p Different forms of devices or contrivances may be employed for effecting this method of breaking up or convertin the columnar and relatively rapid flow ot the incomin liquid to a diffused or distributed, slow and quiescent flow, which will depend upon the form of tank in which the method of settlement is to be carried on', and other conditions of application; but in a tank of the character above described, having a central down 'loY inlet, an advantageous meansof accomplishing the effect describedjs that illustrated in the figure of the accompanying drawing, which shows a tank `adapted to operate according to the invention.

In this tank, l is the inlet conduit, having a vertical delivery portion 2 on its end disposed in the center of the tank, directing the flow of liquid in a downward direction, and toward the bottom; the shape of ythe tank being coned or tapered inward, downward, and of rectangular, circular, or lother suitable form. In this tank. the means of accomplishing the efect described consists of a cup-shaped bucket or reddy vessel?) in front of the inlet orifice 2, into which the infiowing liquid enters, and which has a considerably larger sectional area, say from 3 to S times the area of theinlet orifice 2. The eect of this means is that the direction of flow is practically reversed, and the columnar llow is broken up, and eddies are created; and energy of the liquid ispartly dissipated in neddies, and partly diiused in the greater mass of liquid immediately above the vessel 3.. v

The liquid on emerging. from thel upper part or lip of the cup-vessel l3 hasin generalan upward and spreading action, and this action is controlled and limited by the employment 'of an outer guard device or wall 4; of cylindrical or other suitable shape, which surrounds the vessel 8; and inthe and have an area in Vcross section, say 3 to 8 .times the area 'of the inner vessel3, the most advantageous area depending among other conditions, on the average velocity of the liquid entering b the inlet pipe 2. The

be below it) eddy vessel 3 is pre erably supported from@ the outer guard deviceA, as by hangers V8.

The upward motion of the liquid from the 'vessel'3 is4 limited by the surface of the liquid within the guard' vessel 4, which as shown extends above'` it (but the limit may y be controlled by a cover in vthe cylinder 4' which may be below the level), and is deflected downward with a slow 'and practi-V cally uniform velocity, and emerges therefrom without any disturbing effectupon the deposited sludge and sludge-liquid in the lower portion of' the] tank.y The slud `e is carried ofi1 from the lower portion o the cone bottom of the tank by a pipe 6.

Having produced the Vcondition referred to, the liquid slowly and quietly, without disturbance, ows up through the, larger area ofthe upper part of the tank outside the guard chamber 4,`and is freed of all sludge or solids (provided the rate of inflow is suitable) by the time it reaches the upper"y portion, whence it passes away over the Weir 7 on the outernar'ginpi:l ,the1 tank, which may constltute a continuous weIr, or be I'gapped as shown.:

What is claimed is 1. A settlingtank, an Inl-low pipe,a guard about the delivery end of) said pipe and comprising a cylindrical casing of uniform diameter throughout with open ends above and below said .inflow pipe, and a vessel.'`

closed at bottom and open at top arranged centrally within and-wholly above the lower end of the guard, the inflow pi e directin the material into lthe open end ofsaid vesse 2. A settling tank, an iniow pipe, a guard aboutl the delivery .end of said ipe and comprising a cylindrical casing o uniformv diameter throughout with open ends above and belowsaid iniow pipe, and a vessel closed'at bottom and open at top arranged centrally within and wholly above the lower end of the guard, and means for suspending thevessel from the guard.

In ktestimony whereof I have signed my name to this specification in the presence of,

two subscribing witnesses.

Witnesses:

J ERNEST HARKER,

DAVID C. KERR.

WILLIAM CLIFFORD. f 

